Little Sister
by ToxikCherrys16
Summary: *COMPLETE* Something is wrong with Stiles, and it's worrying everybody; especially her brother, Nico. And he isn't going to stop until he knows what is going on with her, and how to stop it. (Fem!Stiles) Disclaimer - I DO NOT OWN PERCY JACKSON OR TEEN WOLF! (Stiles - Child of Hades series. Part 2/?)


**Hey guys and gals. This is my final fanfic of the year. I know, giving you one as an early Christmas gift. Nobody can say I'm not nice.**

 **Anyway, this is something that people have been asking me for since I posted the first part of the story, and that is some more demigod Stiles. While this might not be exactly what you wanted, it is an idea that stuck with me. I am writing a multi chapter story, I just want to have more done of it before I post.**

 **Now, this story is set BEFORE Little Brother, so the Pack doesn't know about Stiles being a demigod yet. If you are unclear on some of the story, just ask, and I'll tell.**

 **Picture used is 'Beautiful skys over Arizona.'**

 **Enjoy!**

 **T.C**

 **PS. If Stiles were to have a relationship with somebody, do you think it would be another demigod, or somebody from Beacon Hills? And who do you think it would be? I'm just curious if I should put Stiles in a relationship with anybody.**

 **~oOo~**

I didn't know what woke me at first, but when I came to my senses, I knew exactly what it had been. Stiles was across the cabin in her bed, tossing and turning, and gripping the bed sheets, like she was having a nightmare; which considering what she'd been through last month, was a real possibility. What stood out to me though, was that she was murmuring, and what she was murmuring, scared me.

"No, no, no, no, no. Don't let them in. Don't let them…" She faded off; her grip on the sheets seemed to get tighter, "Don't let them in. No, don't let them in."

Her murmuring stopped after that, but she was still breathing too fast, and she was sweating, and she was afraid. Now, I'd seen her scared, and I'd seen her upset – we'd known each other for over three years, and been sharing a cabin for almost a year – but this was different. She wasn't just afraid. She was terrified of whatever was going on in her head.

She remained quiet for a while, only occasionally whispering 'don't let them in' or, 'I need to close the door' or, 'what if they get in?' and just when I thought she was calming down, she bolted up and started screaming; her arms flying around.

Before I knew it, I was out of my bed, and trying to calm her down; trying to keep her arms from moving, as I hugged her from behind. She grabbed my arm, sobbing and gasping for breath; kicking her duvet off to the side, and breathing hard.

Luke burst through the door, his sword glinting in the pale light of the moon and Greek fire. I could hear others running around, some shouting to get Chiron, and others coming towards us, all while I was trying to calm my sister down – who was still crying, and panicking, and weakly fighting.

"What's going on?" Luke asked, his eyes searching the room for any threats, "Are you guys okay? What's wrong with Stiles?"

"Nightmare, I think." I replied, and he lowered his sword, "I don't think she's fully awake. Doubt she even knows what's going on."

"You know dreams are significant to demigods. Do you think this could be something that Chiron needs to know about?" He came over to us, putting a comforting hand on Stiles' knee, "You never know what she's dreaming about, cause she deals with so much more than we do."

I took a deep breath, slackening my tight hold on Stiles as she seemed to have dropped back into an unrestful sleep, "I'll get back to you on that. Something's going on, but I'm not sure what it is. Better not worry anyone if it's nothing."

He bid me goodnight, telling everyone that the scream was a false alarm and that nothing was wrong. It got quiet after that, with everyone going back to their cabins, but I know that not everybody was going to fall back into a peaceful sleep. I knew I definitely wasn't going to. Even with having Stiles settled down in bed, her terrified screams still echoed in my head.

 **~oOo~**

Everything went back to normal for a couple of weeks after the incident, or at least as normal as you can get at Camp Half-Blood. Stiles had Shadow traveled back to Beacon Hills later that day because of school, but something still didn't sit right with me. Will tried to get me to stop worrying, but I could just feel that something was wrong, and I couldn't put my finger on it.

So for the two weeks that Stiles wasn't around, camp went back to the routine of eating, training, campfires, and the usual camp offerings. When she returned, it was a whole other story. Her nightmares seemed to have gone, but something even stranger seemed to have taken its place.

We were in the dining Pavilion having lunch – I was at the Apollo table, because of my doctors note – while Stiles was on her own at the Hades table. She was staring at one of the pillars, furiously writing in a notebook, almost like she was in some kind of trance. Her food as pushed to the side and untouched.

Other campers were starting to take notice of her strange behaviour; even Chiron came down from his place at the Head table to check on her. I was already up from my seat, and waving my hand in front of her face, but it was almost like she couldn't see me. She didn't react, she didn't blink. All she did, was keep writing.

The only time she did react, was when Chiron put a hand on her shoulder and she almost jumped out of her skin. It jolted her out of her trance though, and she looked very confused about where she was.

"Stiles, are you alright?" Chiron asked in a comforting voice.

It took her a few seconds to respond as she took shaky breaths in, but even she didn't seem too sure of her answer. "Yeah, yeah. I… I'm okay. I was… I just fell asleep for a minute."

"You weren't asleep, sis." I told her, sitting across from her, "I'm not quite sure what you were doing, but it wasn't sleeping."

She looked down at the notebook on the table and angrily flipped it over; staring at it like it had wronged her in some way. "I have to get back home. I have to talk to the vet. He'll know what's happening." She tried to stand up but fell back onto the bench.

"How will a vet help you?" One of the other campers asked, almost scoffing at how ridiculous it sounded.

"He's a druid, or at least we think he is. Cryptic, but he knows what he's talking about." Her second attempt at getting up was more successful, but Chiron still grabbed her arm, when she took a step and almost fell again.

"I don't think you're in any shape to Shadow Travel."

"I have to though." She argued, "There're two other people, my friends, that things are happening to. They need to know this, and then we've got to help a Coyote turn back into a girl, and she hasn't been a girl in almost ten years."

Even though Lee, Will, Chiron and I all complained about her trying to go home, she found the nearest shadow, and she was off. Will told me – in no uncertain terms – that I wasn't allowed to follow her, but I wasn't listening to him. I was more focused on Chiron, who was turning over Stiles' notebook.

I walked over to him and looked at the page of the notebook that Stiles had been writing in. All over the page, were the words 'wake up' in a variety of forms and patterns, along with a vertical line of five numbers. 10, 1, 19, 15, 14.

"What do you think it means?"

"I'm not sure." He answered, closing the notebook, and holding it in his hand, "But I plan on finding out what is going on. We should send someone to keep an eye on her."

"I'll go." I volunteered before anybody could say anything.

"And that will be incredibly risky. Two children of Hades, in the same place, would be like carrying a neon sign saying 'come and get me.'"

"But I'm the only person who could keep a low profile. I can hide in the shadows, and a few days can't do that much damage. I can talk to her dad so he can keep a closer eye on her, and follow her round for a couple of days before coming home."

Chiron nodded his head. "You have until daylight fades on Wednesday, no longer. And her father only reports to me on what he observes."

"Understood," I answered, going to my cabin to pack a couple days worth of clothing in a backpack before Shadow Travelling over to Beacon Hills. Something was going on with my sister, and it seemed to be getting worse.

 **~oOo~**

Well, Stiles caught me. She didn't alert anybody to my position, but she looked over towards me a couple of times, but she had bigger things to worry about… Like some doll, a car wreck, and her friend who'd stepped onto the pressure switch of a bear trap, that was meant to catch a Coyote.

Everything turned out all right though. Her friend was saved, Scott got his mojo back, they saved the girl, and everybody ended up not dying. Couldn't say the same thing about myself when Stiles and I ended up talking, but I doubted anything bad would happen, especially when she found out Chiron wanted to see if anything was going on in Beacon Hills, and I had come along instead of having somebody who didn't know about all the Supernatural things that happened in this town.

She accepted the answer, and soon it was back to camp for the both of us. While I stayed at camp full-time, Stiles only came every other weekend - unless something came up with an out of control Alpha, or a rogue Kanima, or just a geriatric who has a thing for beating teenage girls… Or a dark Druid, who was sacrificing humans for power. How Stiles was still sane, remains a mystery to me.

But nothing had happened since the rescue of Malia – the Coyote – so Stiles was currently training with Jason, while I was sat on the sidelines, watching them. Their swords were nearly a blur as they swung at each other, blocking and jabbing.

Stiles kept turning shadows solid, just to annoy him, and it was working. Jason was getting sloppy in his attacks, while Stiles just smiled at him. It was almost like she was trying to goad him into attacking her, and not like she was joking about the fight. She was trying to make him angry enough to actually harm her.

And it worked. Jason soon pointed his Imperial Gold sword at the sky, called upon his powers, and then directed them towards Stiles. Being hit with lightning by the son of Jupiter, must have packed one hell of a punch – given the fact that I have no idea how much Kinetic energy had just been thrown at her.

The energy changed around my sister just slightly, and then it was gone. She sat up and shook her head. "Ow." She murmured, putting a hand to her head, "Guess I should have learned my lesson from when I messed with Thalia."

 **~oOo~**

Beacon Hills didn't seem to get any kind of break from the bullshit the town went through. As soon as Stiles got home, she and Scott played a prank on Coach. Seems harmless enough, until you find out that William Barrow, The Shrapnel Bomber, escaped from the hospital after waking up from general anesthesia – which nobody knows how he did – and went to the school to perform minor surgery on himself. And the prank? That just happened to be the same M.O as when Barrow walked onto a school bus with a shrapnel bomb – killing four students and leaving a fifth with no legs.

He was caught, at a power substation, after he caused a blackout over the entire county when it overloaded. But it was the fact that I got an Iris Message, from Stiles, when she got home that night that scared me. She was panicking, and almost in tears. I'd never seen her like this before.

"I know what the numbers mean."

"What numbers?"

"The numbers I keep writing in my notebook." She told me, looking like she wanted to strangle me for not understanding what she had said the first time, "Somebody left a coded message on the blackboard at school, and Lydia figured it out. The numbers spell Jason."

It took a few seconds to actually process what she'd just told me. Why would she be coding Jason's name in her notebook? Why would somebody put the exact same codes on the school's blackboard – a place hundreds of miles away from where Jason currently was. And why was his name significant?

"I can hear you thinking from here. Don't hurt yourself." She joked, before becoming serious again, "The only connection I can think of between the two, is electricity. Barrow was an electrical engineer, and Jason can summon lighting, which is electrical energy."

"You could be right. I'll tell Chiron about this." It gave her one less thing to worry about, and I could discuss what might be going on with Stiles with him. Whatever it was, it was more serious than we originally thought.

But before I even had a chance to ask to talk to the Centaur – he's a busy guy, you know – a call came through to the Big House, that Stiles had gone missing. She was alone, in nothing but a t-shirt and pajama shorts, in near-freezing conditions, and had called Scott to say that she didn't know where she was, that her leg seemed to be trapped in something, and she was bleeding.

Now, in normal conditions, this would already be a bad situation, but given the fact that she was such a powerful demigod, this was beyond dangerous. Any number of monsters could have taken her, or could find her, and she'd be defenseless against anything that came for her.

Turns out, she was sleeping in a Coyote den and was only found because of something she said to Scott. It was lucky that Scott's father, Agent Rafael McCall of the FBI, understood where she was from that one phrase.

They took her to the hospital to check her over. It didn't take very long for her to fall asleep again, or for another call to come through for me, from Stiles' dad. I always liked the Sheriff. He was funny, sarcastic, was always there for me when I needed him, and he didn't sugarcoat anything, no matter how bad it was.

"Hey, Neeks."

"Hey, Sheriff. How's she doing?"

He paused for a few seconds, and I knew that that meant bad news. "She's okay, at the moment, but they're going to run tests on her in the morning. From the symptoms she's been showing for the past couple of weeks, it's most likely that she's got Frontotemporal Dementia. Areas of your brain start to shrink. It's what killed her mother, and it's the only form of dementia that can hit teenagers."

"But we have medicines. Something at camp can…"

"There's no cure, Nico. I even talked to Chiron when I started to notice what was going on. Asked if he knew of any medicines that could help, and he came up with blanks." He told me, knowing that I would try anything in order not to lose another sister, "Chiron said he would continue to look though. Get in contact with Apollo for his opinion, and Artemis as a last resort, seeming as the Hunters can only die in battle, and will never get sick or grow old. We're doing anything we can.

Everything after that was a bit of a blur. I remembered Will talking to me, but I'm not sure if I answered him, or if I just stayed staring into nothingness. I don't even know if I ate anything, or if I just pushed the food round the plate. We were children of Hades, and yet we couldn't stop Death from coming for us.

 **~oOo~**

Stiles went missing from that night during her MRI scan and didn't turn up for over two days, after leaving a lot of people in the hospital with electrical burns, because she'd tampered with the hospital's electricity in her fugue state.

And the amount of chaos she caused in less than a day, was astounding. She'd rigged a trip wire, connected to an arrow, to hit the first person who tripped it – which just so happened to be Coach Finstock – create panic with a bomb scare with a present that looked like a bomb wrapped by Barrow, and set off an actual bomb at the Sheriff's Station, killing multiple officers in the blast.

We later found out that she wasn't in control of her actions, but nobody at camp had been told exactly what was going on with Stiles, or what was wrong with her, but I knew she was being controlled by something. We just had to figure out what that something was, and not stop till we had an answer.

Before I even had a chance to talk to her though, she checked herself into the local looney bin, Eichen House, where she would stay for at least three days with no contact with the outside world. And it was too risky to IM her, in case a mortal – patient or staff member – saw her talking to somebody who seemed to be floating in mid-air. I didn't want to deal with that.

But, yet again, she escaped from somewhere that was supposed to be secure, by just walking out of the front doors. I mean, this town seems to be amazing at saying places are secure but was actually shit at stopping people from leaving the 'secure places.' Like, they were literally walking past them, and not doing anything.

She turned up at her house though. She might not have stayed long enough for them to catch her, but she was there long enough to set up her chessboard with the names of the Supernaturals on different pieces – with Derek's name on the King, and only one move away from Check Mate.

Want to guess what happened next? She was able to slip through their fingers, yet again. They were literally in the same room, and she was able to just disappear, but that might have something to do with the fact that she can Shadow Travel to begin with, and now whatever is walking around in her body, has figured out how to use it too. That was not good news.

They had an idea about what she was going to do next, and that was to find the last Kaiken – a little dagger that was the physical representation of a Kitsunes tail. After she had that, we had no idea what she was going to do, or where she was going to turn up next.

It didn't take long before we knew though. Somehow, Stiles was able to get past all the enchantments around camp and walk through unnoticed. We only knew that somebody had come in, when we walked into the dining Pavilion for breakfast and saw the message written on the wall in, what looked like blood.

 _CHAOS HAS COME AGAIN._

 **~oOo~**

There was now two Stiles' running around Beacon Hills. You heard me correctly, there are two versions of my sister walking around now after Scott went into her head to guide her the real Stiles out, and just split them in two. Not only that, but Lydia was also taken by the doppelgänger.

Chiron figured out what was going on when he saw the message, and he started wondering how he hadn't noticed the signs before. He'd known that it had happened in Beacon Hills back in the forties when a Kitsune had called upon a Nogitsune – which is a dark Kitsune – to help her get revenge on some of the workers at the internment camp she was held at.

He said that a Nogitsune feeds off of chaos, strife, pain and that they have a dark sense of humor and can become dangerous when offended. It was something truly dangerous, with only two methods of being killed, and it had picked the perfect host.

But why take Lydia. Sure she's a Banshee, but you don't need one to predict death when a child of Hades can sense when somebody is about to die… Unless the Nogitsune lost that power when it was split from Stiles.

Splitting the two of them was a dangerous move, but a smart one. It also put the Nogitsunes original plan out of action, so it had to come up with a new one, as quick as possible. He had to work with what he had, and that was a Banshee, and the distraction of the real Stiles materializing from out of the floor; covered in bandages.

So not only did they have two Stiles running around, they also had to find out where Void Stiles was keeping Lydia. They had help with that one though when another patient of Eichen House – who also happened to be a Banshee too – escaped, and Scott understood exactly what 'coup de foudre' meant.

Oak Creek was where the Nogitsune was first summoned, and where it was first killed, so it seemed fitting that it went there again, to succeed where it hadn't before. It was also the name of the internment camp, and it echoes just like Eichen House does. The screams of the dead would be enough to drive anybody mad.

And all Stiles had to defend herself, was her sword, which was disguised as a baseball bat. The others had claws, bow and arrows, and a katana… And all she had, was her trusty bat.

They all made it out alive though. There was a close call with Allison, but it was only a flesh wound because Stiles decided to use what little strength she had, to clobber the Oni round the head. It caused her to get a gash on her arm, but those were really the worst wounds of the rescue.

However, it did scare a lot of people, when she Shadow Traveled to camp during the campfire, bleeding, and looking like she was about to die. She was pale, thin and just looked like she was getting worse.

Luke, who happened to be sitting closest to where she appeared, caught her when she started to fall, and she started sobbing into his shoulder. She was shaking so much, and I didn't know if it was due to fear, or shock, or a combination of everything that she'd gone through over the past couple of weeks.

"I didn't… I didn't want to… He… He made me do it…"

"Hold up, who made you do what?" Luke asked her, running a thumb over her cheek, almost recoiling when he touched her skin, "You're freezing, Stiles." Somebody handed Luke a blanket, which he draped round her shoulders.

She didn't answer him, but Chiron walked over to her and checked behind her left ear for something before he relaxed. "You are yourself again."

"More me, than the Nogitsune." She looked up at him, her eyes looking even more sunken in the flickering light of the fire, "The final battle is happening tonight. I'm just coming to say goodbye."

"Whatever do you mean?"

Stiles let out an amused chuckle, shakily standing up. "Look at me, Chiron. Does it really look like I'm going to be walking away from this? If I have to die to kill this thing, then I will."

I ran over to my sister and brought her into a hug. I didn't care that she felt like ice, and I didn't care how she looked. She was my sister, and she was willingly walking towards her possible death, to save those she cared about. A Hero and I wouldn't let anybody say any different about her.

 **~oOo~**

Nobody at camp slept that night, just waiting for news on what had happened. I ended up pacing in the office of the Big House, with the other Head Councilors of each cabin around the room. They all looked tired, but they didn't want to sleep, not while they didn't know Stiles' fate.

But no call came through. I was starting to get so anxious, that everywhere I stepped started to freeze. I left the room feeling almost dejected. I had no news to offer to the other campers.

So it was a huge shock, to see Stiles walking over to me; a backpack on one shoulder, and her elbow-length hair over the other. She still looked pale, and tired, and she looked even thinner in the baggy clothes, but she was here, alive, and about as well as you could be after being possessed by a dark spirit.

"Stiles!" I shouted, almost barreling into her, in my haste to wrap my arms around her, "You're still here! Why didn't you call?"

"They took me to the hospital. Been there all night, on a drip and getting stitches. I got twenty for the gash on my arm, and a couple of butterfly bandages for my head, but nothing that won't heal up in a couple of weeks."

"See you're still alive then."

We both turned round to see Annabeth, with her arms folded, and a playful glint in her eyes. "Please don't Judo flip me. I think that probably would kill me." Stiles joked, holding out her hand, "Mind if I borrow your dagger?"

Annabeth looked at her but gave the dagger to her anyway. Stiles let go of my shoulder, twisted her hair round one hand, and then used the weapon to slice through her hair; leaving it just barely touching her shoulders.

"I didn't want to keep looking in the mirror, and seeing what the Nogitsune turned me into." She told us, handing the dagger back to Annabeth, "And a haircut always symbolizes change."

Chiron came walking round the corner, almost taking a step back when he saw Stiles standing on the porch of the Big House, with her now short hair. "Shouldn't you be in the hospital. Why are you here?"

"I, er… I need to clear my head. And I wanted to do that at camp." She told him, rubbing the back of her neck, "I can't do it at home, because of everything I've done over the past few weeks. Too many memories."

He seemed to take that into consideration before he smiled and nodded towards us. "Very well. Take a few days off, get checked out by Apollo's kids, and then you start training again when they give you the all clear."

"Thank you, Chiron."

Just as we were turning to leave, Chiron called Stiles' name again; making us turn towards him. "I'm glad to see that you are feeling better. Life around here might've been a little boring without you."  
Stiles started laughing, and it was really nice to hear it, especially after everything that had happened, and everything that could've gone wrong. "Boring? At camp? I'm not sure camp could ever be boring, Chiron. After all, if I wasn't here, you'd still have the Stoll's to deal with, and they are anything but predictable."


End file.
